Certain items such as food and beverages are often sold and stored in product containers. In many instances, a consumer periodically performs a visual check to inventory contents remaining in food and beverage containers. In another example, bar and restaurant operators periodically inventory the amount of content left in bottles to determine the amount sold and identify quantity and type of products to be purchased/replenished. The inventory of content remaining in product containers has been traditionally determined manually. This manual process is often laborious, imprecise, and error prone. For example, it is often difficult for a person to visually determine an amount of liquid beverage remaining in a bottle with precision in a reliable manner. In commercial settings, the amount of time spent by an employee to manually inventory the remaining content represents a real employment cost realized by the employer. Therefore, there exists a need for a better way to determine the amount of content remaining in a container.